- Hydrosilylative reduction of primary amides to primary amines catalyzed by a terminal [Ni-OH] complex
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A terminal [Ni-OH] complex1, supported by triflamide-functionalized NHC ligands, catalyzes the hydrosilylative reduction of a range of primary amides into primary amines in good to excellent yields under base-free conditions with key functional group tolerance. Catalyst1is also effective for the reduction of a variety of tertiary and secondary amides. In contrast to literature reports, the reactivity of1towards amide reduction follows an inverse trend,i.e., 1° amide > 3° amide > 2° amide. The reaction does not follow a usual dehydration pathway.
- Bera, Jitendra K.,Pandey, Pragati
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supporting information
p. 9204 - 9207
(2021/09/20)
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- Transition metal-free catalytic reduction of primary amides using an abnormal NHC based potassium complex: Integrating nucleophilicity with Lewis acidic activation
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An abnormal N-heterocyclic carbene (aNHC) based potassium complex was used as a transition metal-free catalyst for reduction of primary amides to corresponding primary amines under ambient conditions. Only 2 mol% loading of the catalyst exhibits a broad substrate scope including aromatic, aliphatic and heterocyclic primary amides with excellent functional group tolerance. This method was applicable for reduction of chiral amides and utilized for the synthesis of pharmaceutically valuable precursors on a gram scale. During mechanistic investigation, several intermediates were isolated and characterized through spectroscopic techniques and one of the catalytic intermediates was characterized through single-crystal XRD. A well-defined catalyst and isolable intermediate along with several stoichiometric experiments, in situ NMR experiments and the DFT study helped us to sketch the mechanistic pathway for this reduction process unravelling the dual role of the catalyst involving nucleophilic activation by aNHC along with Lewis acidic activation by K ions.
- Bhunia, Mrinal,Sahoo, Sumeet Ranjan,Das, Arpan,Ahmed, Jasimuddin,Sreejyothi,Mandal, Swadhin K.
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p. 1848 - 1854
(2020/03/03)
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- Direct cycle between co-product and reactant: An approach to improve the atom economy and its application in the synthesis and protection of primary amines
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Two important goals of green chemistry are to maximize the efficiency of reactants and to minimize the production of waste. In this study, a novel approach to improve the atom economy of a chemical process was developed by incorporating a direct cycle between a co-product and a reactant of the same reaction. To demonstrate this concept, recoverable 3,4-diphenylmaleic anhydride (1) was designed and used for the atom-economical synthesis of aliphatic primary amines from aqueous ammonia. In each individual cycle, only ammonia and alkyl halide were consumed, and 1 was recovered in nearly a quantitative yield. In this approach for developing atom-economical protecting agents, 1 showed good performance as a recoverable protecting agent for primary amines. The broad substrate scope, good tolerance to various reaction conditions, and high reaction and recovery rates make 1 a valuable complement to conventional primary amine protecting agents.
- Guan, Qi,Jiang, Mingyang,Wu, Junhui,Zhai, Yanpeng,Wu, Yue,Bao, Kai,Zhang, Weige
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supporting information
p. 5794 - 5799
(2016/11/06)
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- A proton-switchable bifunctional ruthenium complex that catalyzes nitrile hydroboration
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A new bifunctional pincer ligand framework bearing pendent proton-responsive hydroxyl groups was prepared and metalated with Ru(II) and subsequently isolated in four discrete protonation states. Stoichiometric reactions with H2 and HBPin showed facile E-H (E = H or BPin) activation across a Ru(II)-O bond, providing access to unusual Ru-H species with strong interactions with neighboring proton and boron atoms. These complexes were found to promote the catalytic hydroboration of ketones and nitriles under mild conditions, and the activity was highly dependent on the ligand's protonation state. Mechanistic experiments revealed a crucial role of the pendent hydroxyl groups for catalytic activity.
- Geri, Jacob B.,Szymczak, Nathaniel K.
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p. 12808 - 12814
(2015/10/28)
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- Preparation of a clinically investigated ras farnesyl transferase inhibitor
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The synthesis of ras farnesyl-protein transferase inhibitor 1 is described on a multi-kilogram scale. Retrosynthetic analysis reveals chloromethylimidazole 2 and a piperazinone 3 as viable precursors. The 1,5-disubstituted imidazole system was regioselectively assembled via an improved Marckwald imidazole synthesis. A new imidazole dethionation procedure has been developed to convert the Marckwald mercaptoimidazole product to the desired imidazole. This methodology was found to be tolerant of a variety of functional groups providing good to excellent yields of 1,5-disubstituted imidazoles. A new Mitsunobu cyclization strategy was developed to prepare the arylpiperazinone fragment 3.
- Maligres, Peter E.,Waters, Marjorie S.,Weissman, Steven A.,McWilliams, J. Christopher,Lewis, Stephanie,Cowen, Jennifer,Reamer, Robert A.,Volante,Reider, Paul J.,Askin, David
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p. 229 - 241
(2007/10/03)
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- Substituted polycyclic aryl and heteroaryl pyrazinones useful for selective inhibition of the coagulation cascade
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The invention relates to substituted polycyclic aryl and heteroaryl pyrazinone compounds useful as inhibitors of serine proteases of the coagulation cascade and compounds, compositions and methods for anticoagulant therapy for the treatment and prevention of a variety of thrombotic conditions including coronary artery and cerebrovascular diseases.
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Page column 119
(2012/01/30)
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- Pyrrolidine modulators of chemokine receptor activity
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The present invention is directed to pyrrolidine compounds of the formula I: (wherein R1, R2, R3, R4, R5, R6and n are defined herein) which are useful as modulators of chemokine receptor activity. In particular, these compounds are useful as modulators of the chemokine receptors CCR-5 and/or CCR-3.
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- INHIBITORS OF PRENYL-PROTEIN TRANSFERASE
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The present invention comprises piperazine/piperazinone-containing compounds having multicyclic ring system substituents on one of the piperazine/piperazinone nitrogens, which inhibit prenyl-protein transferases, including farnesyl-protein transferase and geranylgeranyl-protein transferase type I. Such therapeutic compounds are useful in the treatment of cancer
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Page column 59
(2010/01/21)
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- Process for producing salts of cyanobenzylamines
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A process for producing a salt of a cyanobenzylamine comprising reacting a cyanobenzylamine with an acid. A salt of a cyanobenzylamine can industrially easily be produced and the resulting salt of a cyanobenzylamine has a high bulk density.
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Page column 8
(2008/06/13)
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- Inhibitors of prenyl-protein transferase
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The present invention is directed to conformationally constrained compounds which inhibit prenyl-protein transferase and the prenylation of the oncogene protein Ras. The invention is further directed to chemotherapeutic compositions containing the compounds of this invention and methods for inhibiting prenyl-protein transferase and the prenylation of the oncogene protein Ras.
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- Process for producing salts of cyanobenzylamines
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A process for producing a salt of a cyanobenzylamine comprising reacting a cyanobenzylamine with an acid. A salt of a cyanobenzylamine can industrially easily be produced and the resulting salt of a cyanobenzylamine has a high bulk density.
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- Process for making 1,5-disubstituted imidazoles
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The present invention is directed to a process for synthesizing 1,5-disubstituted imidazoles, which are useful in the preparation of farnesyl-protein transferase inhibitors.
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